Dynamics of Nanoparticle Chain Aggregates of Carbon Under Tension

AbstractCarbon black in the form of nanoparticle chains is used as a reinforcing filler in elastomers. However, the dynamics of the filler particles under tension and their role in the improvement of the mechanical properties of rubber are not well understood. We have studied experimentally the dynamics of isolated nanoparticle chain aggregates (NCAs) of carbon made by laser ablation, and also that of carbon black embedded in a polymer film. In situ studies of stretching and contraction of such chains in the transmission electron microscope (TEM) were conducted under different maximum values of strain. Stretching causes initially folded NCA to reorganize into a straight, taut configuration. Further stretching leads to either plastic deformation and breakage (at 37.4% strain) or to a partial elastic behavior of the chain at small strains (e.g. 2.3% strain). For all cases the chains were very flexible under tension. Similar reorientation and stretching was observed for carbon black chains embedded in a polymer film. Such flexible and elastic nature of NCAs point towards a possible mechanism of reinforcement of rubber by carbon black fillers.

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Direct Characterization of the Relation between the Mechanical Response and Microstructure Evolution in Aluminum by Transmission Electron Microscopy In Situ Straining

Materials ◽

10.3390/ma14061431 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1431

Author(s):

Seiichiro Ii ◽

Takero Enami ◽

Takahito Ohmura ◽

Sadahiro Tsurekawa

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Ion Beam ◽

Elastic Behavior ◽

Annealed Specimen ◽

Displacement Curve ◽

Dislocation Loops ◽

Transmission Electron ◽

Stress Drops

Transmission electron microscopy in situ straining experiments of Al single crystals with different initial lattice defect densities have been performed. The as-focused ion beam (FIB)-processed pillar sample contained a high density of prismatic dislocation loops with the <111> Burgers vector, while the post-annealed specimen had an almost defect-free microstructure. In both specimens, plastic deformation occurred with repetitive stress drops (∆σ). The stress drops were accompanied by certain dislocation motions, suggesting the dislocation avalanche phenomenon. ∆σ for the as-FIB Al pillar sample was smaller than that for the post-annealed Al sample. This can be considered to be because of the interaction of gliding dislocations with immobile prismatic dislocation loops introduced by the FIB. The reloading process after stress reduction was dominated by elastic behavior because the slope of the load–displacement curve for reloading was close to the Young’s modulus of Al. Microplasticity was observed during the load-recovery process, suggesting that microyielding and a dislocation avalanche repeatedly occurred, leading to intermittent plasticity as an elementary step of macroplastic deformation.

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Effect of Heat Sinks on Visco-Elastic & Mechanical Properties of EPDM Based Ablative Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.442.52 ◽

2010 ◽

Vol 442 ◽

pp. 52-58

Author(s):

M.A. Bashir ◽

H. Ahmad ◽

R. Ahmed ◽

R.A. Alvi ◽

Mohammad Bilal Khan

Keyword(s):

Mechanical Properties ◽

Carbon Fiber ◽

Glass Fiber ◽

Heat Sinks ◽

Elastic Behavior ◽

Fiber Glass ◽

Adverse Conditions ◽

Reinforcing Fillers ◽

Heat Shielding ◽

Reinforcing Filler

Ablative composites are heat shielding, protective materials that are being used in aerospace industry to protect inner hardware and sensitive devices. The aero dynamic vehicles have to face high stresses, ultra high temperature and adverse conditions of air friction. It is required to develop the materials with light weight and high modulus. EPDM, being heat and ozone attack resistant is the best candidate for the preparation of ablative composites by introducing different heat sinks such as silica, glass fiber, carbon fiber, asbestos, carbon and their combinations have been studied in this work. The prepared materials were tested and it was found that visco elastic behavior of the composites affected by the addition of reinforcing filler (carbon, silica), semi-reinforcing filler (carbon fiber, glass fiber) and non-reinforcing filler (asbestos powder). Mechanical properties tested at different rates, revealed the improvement in tensile strength and % elongation in case of reinforcing and semi-reinforcing fillers but showed adverse effect in case of non-reinforcing fillers. Rheological investigations of these novel composites shows that moony viscosity of the materials containing glass fiber, carbon fiber, silica decreases in the order glass fiber > carbon fiber > silica.

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Preparation of UHMWPE/carbon black nanocomposites by in situ Ziegler–Natta catalyst and investigation of product thermo-mechanical properties

Polymer Bulletin ◽

10.1007/s00289-015-1536-8 ◽

2015 ◽

Vol 73 (4) ◽

pp. 1085-1101 ◽

Cited By ~ 5

Author(s):

Seyedeh Alaleh Sadrani ◽

S. A. Ahmad Ramazani ◽

Seyedeh Elham Khorshidiyeh ◽

Narges Jafari Esfad

Keyword(s):

Mechanical Properties ◽

Carbon Black ◽

Natta Catalyst ◽

Ziegler Natta Catalyst

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Iron Oxide Nanoparticles Obtained from a Fe(II) - Chitosan Polymer Film

Materials Science Forum ◽

10.4028/www.scientific.net/msf.644.51 ◽

2010 ◽

Vol 644 ◽

pp. 51-55 ◽

Cited By ~ 1

Author(s):

Juan Fco Luna Martínez ◽

E. Reyes-Melo ◽

Virgilio González-González ◽

A. Torres-Castro ◽

Carlos Guerrero-Salazar ◽

...

Keyword(s):

Iron Oxide ◽

Composite Film ◽

Polymer Film ◽

Iron Oxide Nanoparticles ◽

Magnetic Behavior ◽

Nanostructured Material ◽

Oxide Nanoparticles ◽

Transmission Electron ◽

Alkaline Conditions

In this work, iron oxide nanoparticles (~5 nm) embedded in a chitosan polymer film, were synthesized. In order to obtain this nanostructured material, firstly a homogenous film of Fe(II)-chitosan was prepared. The resulting composite film has a thickness of ~140μm. Iron oxide nanoparticles were in-situ synthesized by treating the composite film with H2O2 under alkaline conditions. The morphological analysis by Transmission Electron Microscopy (TEM) shows the nanoparticles were embedded and stabilized in chitosan polymer film. The magnetic behavior was studied by magnetization measurements. The magnetization curves at room temperature showed that iron oxide nanoparticles have a superparamagnetic behavior.

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TEM Nanostructure Manipulation Device for in Situ Study of Elastic Behavior of Nanoparticle Chain Aggregates

Microscopy and Microanalysis ◽

10.1017/s1431927602103722 ◽

2002 ◽

Vol 8 (S02) ◽

pp. 1130-1131

Author(s):

Y.J. Suh ◽

S.V. Prikhodko ◽

S.K. Friedlander

Keyword(s):

Elastic Behavior ◽

In Situ Study ◽

Chain Aggregates

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TEM observation of precipitates and their role to mechanical properties in Ti-5553 alloy heated to some temperatures up to 923 K

MATEC Web of Conferences ◽

10.1051/matecconf/202032111035 ◽

2020 ◽

Vol 321 ◽

pp. 11035

Author(s):

E. Sukedai ◽

E. Aeby-Gautier ◽

M. Dehmas

Keyword(s):

Electron Microscopy ◽

Mechanical Properties ◽

Hardening Mechanism ◽

Transmission Electron ◽

The Matrix ◽

Higher Temperature ◽

Shearing Mechanism ◽

Hardness Values ◽

Measured Hardness

A Ti-5553 specimen was continuously heated to 923 K and simultaneously in-situ HEXRD profiles were taken. In addition, specimens heated at the same rate to several temperatures up to 923 K and further quenched were observed by transmission electron microscopy. Based on both results obtained, transformation sequence was clarified, precipitations of ω-, α”iso- and α-phases were confirmed, and size and density of these precipitates were measured. Hardness values of those specimens were also measured. The hardening mechanism was considered as shearing-mechanism for specimens aged at lower temperatures and by-pass one for specimens aged at higher temperature. An attempt of distinction between α”iso - and α-precipitates was also tried. Both precipitates were in needle-like shape and a possibility was suggested by measuring angles between two needle-shape precipitates on {110} of the matrix and comparing with each other.

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